I'm with you on everything except the made-up cities.
I LOVE 'em.
Everyone can own them, like Springfield in The Simpsons.
Plus, you don't have to worry about "what does that building look like" and "do those streets even connect.
If you need a story in a park, your city has a park. if you need a warehouse district, a zoo, a library, what have you...your city can have it.
It's like having your own president for your world. Yeah, Obama's been all over the Marvel, Image and other universes, though not DC. DC seems to have learned that using a real president puts a time stamp on your universe. presidents serve 4 years. They can serve up to two terms. If you have a character in his mid twenties to mid thirties shaking Kennedy's hand in the sixties (Superman) and Reagan's hand in the Eighties (Superman again) And Clinton's hand in the 90's (Yup, Supes) you just made superman at least 50 something years old IN CONTINUITY. Not good.
I realize I've strayed a bit from our made-up cities. But basically it says from the get go "Look, this is only 90% OUR world, and 10% made-up-Sci-Fi/Fantasy Superhero world, and that 10% will account for any and all differences intended or mistaken, from our real world and its history."
Powerful statement that frees up a LOT of story room. Plus, real cities change. Building go up, they come down, and just like the presidents, that can put a time stamp on things. A shot of Spidey swinging between the Twin Towers lets you know how long he's been patrolling NYC.
Plus, When DC sank part of San Diego to create Sub-Diego it broke that sense of "I'm there". However if you have earthquakes tear up Gotham, everyone can accept that a LOT easier.
And don't try and dub this "lazy writing" either! Done right, you may not have to RESEARCH your city, but you DO have to keep an accurate accounting of where you put what. You readers will remember that St. Forby's Cathedral was in downtown Editor's Ville in issue 2 but is overlooking the river in issue 7.
So, yeah, having the real cities as backdrops when you NEED them, but basing most things in your won fictional cities is perfectly feasible.